* Phosphate group: This is a negatively charged group consisting of a phosphorus atom bonded to four oxygen atoms.

* Sugar: This is a five-carbon sugar. In DNA, the sugar is deoxyribose; in RNA, it is ribose.

The part that varies in a nucleotide is the nitrogenous base. There are five main types of nitrogenous bases: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U). Adenine and guanine are purines, which have two rings, while cytosine, thymine, and uracil are pyrimidines, which have one ring.

* DNA: A, G, C, and T

* RNA: A, G, C, and U

The specific sequence of these nitrogenous bases within a DNA or RNA molecule determines the genetic information it carries.